There are many industrially useful materials among α,β-unsaturated carboxylic acids. For example, acrylic acid and methacrylic acid are quite largely used for raw materials of synthetic resins and the like.
As a method for producing an α,β-unsaturated carboxylic acid, a method of liquid-phase oxidation of an olefin or an α,β-unsaturated aldehyde with molecular oxygen has been researched. As a catalyst for producing the α,β-unsaturated carboxylic acid through liquid-phase oxidation of the olefin or the α,β-unsaturated aldehyde with molecular oxygen, for example, a palladium-containing catalyst is proposed in Patent Document 1. Further, as the catalyst for producing the α,β-unsaturated carboxylic acid through liquid-phase oxidation of the olefin with molecular oxygen, a palladium-containing catalyst which contains an intermetallic compound between palladium and lead, bismuth, thallium or mercury is proposed in Patent Document 2.
As a palladium-containing catalyst suitable for producing benzyl acetate, though not for producing a carboxylic acid, a catalyst having an atomic ratio of palladium/bismuth being 3/1.4 to 3/0.8 for producing a carboxylic acid ester is proposed in Patent Document 3. A catalyst having an atomic ratio of palladium/bismuth being 2.5 to 3.5 for producing benzyl acetate is proposed in Patent Document 4.    Patent Document 1: Japanese Patent Application Laid-Open No. 2004-141,863    Patent Document 2: Japanese Patent Application Laid-Open No. Sho 56-59,722    Patent Document 3: Japanese Patent Application Laid-Open No. Hei 10-263,399    Patent Document 4: Japanese Patent Application Laid-Open No. Hei 10-7,616